U.S. patent application number 11/330957 was filed with the patent office on 2007-07-12 for lightweight armor wires for electrical cables.
Invention is credited to Garud Sridhar, Joseph P. Varkey.
Application Number | 20070158095 11/330957 |
Document ID | / |
Family ID | 38198075 |
Filed Date | 2007-07-12 |
United States Patent
Application |
20070158095 |
Kind Code |
A1 |
Sridhar; Garud ; et
al. |
July 12, 2007 |
Lightweight armor wires for electrical cables
Abstract
Disclosed are electric cables with improved armor wires used
with wellbore devices to analyze geologic formations adjacent a
wellbore. The cables include at least one insulated conductor, and
one or more armor wires surrounding the insulated conductor. The
armor wires include a low density core surrounded by a corrosion
resistant alloy clad, where the alloy clad includes such alloys as
beryllium-copper based alloys, nickel-chromium based alloys,
superaustenitic stainless steel alloys, nickel-cobalt based alloys,
nickel-molybdenum-chromium based alloys, and the like. The low
density core may be based upon titanium or titanium alloys. The
cables of the invention may be any useful electric cable design,
including monocables, quadcables, heptacables, quadcables,
slickline cables, multiline cables, coaxial cables, or seismic
cables.
Inventors: |
Sridhar; Garud; (Stafford,
TX) ; Varkey; Joseph P.; (Missouri City, TX) |
Correspondence
Address: |
SCHLUMBERGER IPC;ATTN: David Cate
555 INDUSTRIAL BOULEVARD, MD-21
SUGAR LAND
TX
77478
US
|
Family ID: |
38198075 |
Appl. No.: |
11/330957 |
Filed: |
January 11, 2006 |
Current U.S.
Class: |
174/106R |
Current CPC
Class: |
H01B 7/2806 20130101;
H01B 7/046 20130101; H01B 3/30 20130101; G01V 1/201 20130101; G01V
1/52 20130101 |
Class at
Publication: |
174/106.00R |
International
Class: |
H01B 9/02 20060101
H01B009/02 |
Claims
1. An electric cable comprising at least one insulated conductor
and at least one armor wire layer surrounding the insulated
conductor, wherein the armor wire layer comprises armor wires
comprising a low density core and a corrosion resistant alloy outer
clad, provided the core is not comprised of a copper conductor.
2. A cable according to claim 1 wherein the insulated conductor
comprises at least one electrical conductor encased in an
insulating material.
3. A cable according to claim 1 where a bonding layer is placed
between the low density core and the corrosion resistant alloy
clad.
4. A cable according to claim 1 the at least one armor wire layer
comprises a first armor wire layer surrounding the insulated
conductor and a second armor wire layer served around the first
armor wire layer.
5. A cable according to claim 1 further comprising a polymeric
material disposed in interstitial spaces formed between the armor
wires, as well as formed between the armor wires and insulated
conductor.
6. A cable according to claim 2 wherein the insulation material is
selected fiom the group conisisting of polyolefins,
polyaryletherether ketone, polyaryl ether ketone, polyphenylene
sulfide, modified polyphenylene sulfide, polymers of
ethylene-tetrafluoroethylene, polymers of poly(1,4-phenylene),
polytetrafluorocthylene, perfluoroalkoxy polymers, fluorinated
ethylene propylene,
polytetrafluoroethylene-perfluoromethylvinylether polymers,
polyamide, polyurethane, thermoplastic polyurethane, chlorinated
ethylene propylene, ethylene chloro-trifluorocthylene, and any
mixtures thereof.
7. A cable according to claim 1 wherein the low density core is
titanium or any titanium alloy, and the corrosion resistant alloy
clad is an alloy comprising nickel in an amount from about 10% to
about 60% by weight of total alloy weight, chromium in an amount
from about 15% to about 30% by weight of total alloy weight,
molybdenum in an amount from about 2% to about 20% by weight of
total alloy weight, and cobalt in an amount up to about 50% by
weight of total alloy weight.
8. A cable according to claim 1 wherein the corrosion resistant
alloy clad comprises an alloy selected from the group consisting of
beryllium-copper based alloys, copper-nickel-tin based alloys,
superaustenitic stainless steel alloys, nickel-cobalt based alloys,
nickel-chromium based alloys, nickel-molybdenum-chromium based
alloys, and any mixtures thereof.
9. A cable according to claim 1 wherein the corrosion resistant
alloy clad comprises a nickel-chromium based alloy or a
nickel-cobalt based alloy.
10. A cable according to claim 2 wherein the insulating material
comprises: (a) a first insulating jacket layer disposed around the
metallic conductors wherein the first insulating jacket layer has a
first relative permittivity; and (b) a second insulating jacket
layer disposed around the first insulating jacket layer and having
a second relative permittivity that is less than the first relative
permittivity; wherein the first relative permittivity is within a
range of about 2.5 to about 10.0, and wherein the second relative
permittivity is within a range of about 1.8 to about 5.0.
11. A cable according to claim 1 which has an outer diameter from
about 0.5 mm to about 400 mm.
12. A cable according to claim 1 wherein the cable is a seismic
cable, or a wellbore cable selected from the group consisting of
monocable, a quadcable, a heptacable, a quadcable, slickline cable,
multiline cable, and a coaxial cable.
13. A wellbore electrical cable according to claim 1 wherein the at
least one insulated conductor comprises seven metallic conductors
encased in an insulating material, and wherein the at lest one
armor wire layer comprises a first layer of armor wires surrounding
the insulated conductor and a second layer of armor wires surrounds
the first layer of armor wires.
14. A wellbore electrical cable according to claim 13 wherein the
at least one insulated conductor comprise seven insulated
conductors in a heptacable design.
15. An electric cable according to claim 1 wherein the corrosion
resistant alloy clad is extruded over the low density core, and the
clad and core are drawn to form the armor wires.
16. An electric cable according to claim 1 wherein the corrosion
resistant alloy clad is at least one sheath of corrosion resistant
alloy formed over the low density core, and the clad and core are
drawn to form the armor wires.
17. An electric cable according to claim 1 wherein the low density
core has a density up to about 4.8 g/cm.sup.3.
18. An electric cable according to claim 17 wherein the low density
core has a density from about 4.2 g/cm.sup.3 to about 4.8
g/cm.sup.3.
19. A cable according to claim 4 further comprising a polymeric
material disposed in interstitial spaces formed between the armor
wires, as well as formed between the armor wires and insulated
conductor, and further wherein the polymeric material forms a
polymeric jacket around the periphery of the second armor wire
layer.
20. A method for manufacturing an electrical cable comprising: (a)
forming an armor wire by: (i) providing a low density core, (ii)
bringing the low density core into contact with at least one sheath
of corrosion resistant alloy material, (iii) forming the sheet of
corrosion resistant alloy material around the low density core, and
drawing the combination of the alloy material and core to a final
diameter to form the armor wire; (b) providing at least one
insulated conductor; (c) serving a first layer of armor wires
around the insulated conductor; and, (d) serving a second layer of
armor wires around the first layer of armor wires.
21. A method according to claim 20 further comprising coating the
low density core with a bonding layer before forming the sheath of
corrosion resistant alloy material around the low density core.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to electric cables, and methods of
manufacturing and using such cables. In one aspect, the invention
relates to electric cables with light weight corrosion resistant
armor wires used with wellbore devices to analyze geologic
formations adjacent a wellbore, methods of manufacturing same, as
well as uses of such cables.
[0002] Generally, geologic formations within the earth that contain
oil and/or petroleum gas have properties that may be linked with
the ability of the formations to contain such products. For
example, formations that contain oil or petroleum gas have higher
electrical resistivity than those that contain water. Formations
generally comprising sandstone or limestone may contain oil or
petroleum gas. Formations generally comprising shale, which may
also encapsulate oil-bearing formations, may have porosities much
greater than that of sandstone or limestone, but, because the grain
size of shale is very small, it may be very difficult to remove the
oil or gas trapped therein. Accordingly, it may be desirable to
measure various characteristics of the geologic formations adjacent
to a well before completion to help in determining the location of
an oil- and/or petroleum gas-bearing formation as well as the
amount of oil and/or petroleum gas trapped within the formation.
The zones to be analyzed can be vertically underneath the well bore
surface opening or at angles deviated up to 90 degrees or more from
the main well bore.
[0003] Logging tools, which are generally long, pipe-shaped devices
may be lowered into the well to measure such characteristics at
different depths along the well. These logging tools may include
gamma-ray emitters/receivers, caliper devices,
resistivity-measuring devices, neutron emitters/receivers, and the
like, which are used to sense characteristics of the formations
adjacent the well. A wireline cable connects the logging tool with
one or more electrical power sources and data analysis equipment at
the earth's surface, as well as providing structural support to the
logging tools as they are lowered and raised through the well.
Generally, the wireline cable is spooled out of a truck or an
offshore platform unit, over a pulley, and down into the well.
[0004] Wireline cables are typically formed from a combination of
metallic conductors, insulative materials, filler materials,
jackets, and metallic armor wires. Armor wires typically perform
many functions in wireline cables, including protecting the
electrical core from the mechanical abuse seen in typical downhole
environment, and providing mechanical strength to the cable to
carry the load of the tool string and the cable itself.
[0005] Armor wire performance may also be dependent on corrosion
protection. Harmful fluids in the downhole environment may cause
armor wire corrosion, and once the armor wire begins to corrode,
strength and pliability may be quickly compromised. Although the
cable core may still remain functional, it is not economically
feasible to replace the armor wire(s), and the entire cable must
typically be discarded.
[0006] Conventionally, wellbore electrical cables utilize
galvanized steel armor wires (typically plain carbon steels in the
range AISI 1065 and 1085), known in the art as Galvanized Improved
Plow Steel (GIPS) armor wires, which do provide high strength. Such
armor wires are typically constructed of cold-drawn pearlitic steel
coated with zinc for moderate corrosion protection. The GIPS armor
wires are protected by a zinc hot-dip or electrolytic coating that
acts as a sacrificial layer when the wires are exposed to moderate
environments.
[0007] Commonly, sour well cables constructed completely of
corrosion resistant alloys are used in sour well downhole
conditions. While such alloys are well suited for forming armor
wires used in cables for such wells, it is commonly known that the
strength of such alloys is very limited.
[0008] As deviations in the well bores are increasing, the zones to
be reached for evaluation or production may be at large angles
relative to the well bore opening. To reach these zones, the cable
must be tractored, but the reach may be limited as cables with
galvanized steel armor wires may not be sufficiently light to
satisfy these requirements. Furthermore, deviated well bores are
typically sour as higher concentrations of corrosive agents are
typically present.
[0009] Thus, a need exists for electric cables that are low weight
with improved corrosion and abrasion protection. An electrical
cable that can overcome one or more of the problems detailed above
while conducting larger amounts of power with significant data
signal transmission capability, would be highly desirable, and the
need is met at least in part by the following invention.
BRIEF SUMMARY OF THE INVENTION
[0010] In one aspect, the invention relates to electric cables with
enhanced armor wires used with wellbore devices to analyze geologic
formations adjacent a wellbore. The cables include at least one
insulated conductor, and one or more armor wire layers surrounding
the insulated conductor. The lightweight design of the armor wires
used in the armor wire layers include a low density core surrounded
by a corrosion resistant alloy clad (outer layer), such as a nickel
based alloy, for example. A bonding layer may also be placed
between the low density core and corrosion resistant alloy clad.
The electrical cables may include a first armor wire layer
surrounding the insulated conductor, and a second armor wire layer
served around the first armor wire layer. The cables of the
invention may be useful for a variety of applications including
cables in subterranean operations, such as a monocable, a
quadcable, a heptacable, slickline cable, multiline cable, a
coaxial cable, or a seismic cable.
[0011] Any suitable material for forming a low density core may be
used. Examples of such materials include titanium and its alloys,
including, but not necessarily limited to alpha (or near alpha)
alloys, beta alloys (i.e. Beta-C), alpha-beta alloys (i.e.
Ti-6A1-4V), and the like. Materials useful to form the corrosion
resistant alloy clad of the armor wires include, by non-limiting
example, such alloys as copper-nickel-tin based alloys,
beryllium-copper based alloys, nickel-chromium based alloys,
superaustenitic stainless steel alloys, nickel-cobalt based alloys
and nickel-molybdenum-chromium based alloys, and the like, or any
mixtures thereof.
[0012] Insulation materials used to form insulated conductors
useful in cables of the invention is include, but are not
necessarily limited to, polyolefins, polyaryletherether ketone,
polyaryl ether ketone, polyphenylene sulfide, modified
polyphenylene sulfide, polymers of ethylene-tetrafluoroethylene,
polymers of poly(1,4-phenylene), polytetrafluoroethylene,
perfluoroalkoxy polymers, fluorinated ethylene propylene,
polytetrafluoroethylene-perfluoromethylvinylether polymers,
polyamide, polyurethane, thermoplastic polyurethane, chlorinated
ethylene propylene, ethylene chloro-trifluoroethylene, and any
mixtures thereof. Appropriate conductors are readily known to those
in the art.
[0013] In another aspect, the invention relates to methods for
preparing an electrical cable which includes forming the armor
wires used to form the armor wire layers, providing at least one
insulated conductor, serving a first layer of the armor wires
around the insulated conductor, and serving a second layer of the
same armor wires around the first layer of the armor wires. In one
approach, the enhanced design of the armor wires are prepared by
providing low density core, bringing the core strength member into
contact with at least one sheets of a corrosion resistant alloy
clad material, forming the sheet of alloy material around the high
strength core, and drawing the combination of the alloy material
and core strength member to a final diameter to form the
lightweight design of the armor wire. Another approach to preparing
the armor wires includes providing a low density core, extruding an
alloy material around the core, and drawing the combination of the
alloy material and core strength member to a final diameter to form
the armor wire. The preparation of armor wires may also include
coating the low density core with a bonding layer before forming
the alloy clad material around the low density core.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The invention may be understood by reference to the
following description taken in conjunction with the accompanying
drawings:
[0015] FIG. 1 is a cross-sectional view of a typical prior art
cable design.
[0016] FIG. 2 is a stylized cross-sectional representation of an
armor wire design useful in some cables of the invention.
[0017] FIG. 3 is a cross-sectional representation of a general
cable design according to the invention using two layers of armor
wires
[0018] FIG. 4 is a cross-sectional representation of a heptacable
design according to the invention, including two layers of armor
wires.
[0019] FIG. 5 represents, by stylized cross-section, a monocable
design according to the invention.
[0020] FIG. 6 illustrates a method of preparing armor wires useful
in cables according to the invention.
[0021] FIG. 7 illustrates another method of preparing some armor
wires useful in cables according to the invention.
[0022] FIG. 8 illustrates yet another method of preparing some
armor wires.
[0023] FIG. 9 is a cross-sectional representation of cables of the
invention which include a polymeric material disposed about the
armor wires
DETAILED DESCRIPTION OF THE INVENTION
[0024] Illustrative embodiments of the invention are described
below. In the interest of clarity, not all features of an actual
implementation are described in this specification. It will of
course be appreciated that in the development of any such actual
embodiment, numerous implementation-specific decisions must be made
to achieve the developer's specific goals, such as compliance with
system related and business related constraints, which will vary
from one implementation to another. Moreover, it will be
appreciated that such a development effort might be complex and
time consuming but would nevertheless be a routine undertaking for
those of ordinary skill in the art having the benefit of this
disclosure.
[0025] The invention relates to electrical cables and methods of
manufacturing the same, as well as uses thereof. In one aspect, the
invention relates to an electrical cables used with devices to
analyze geologic formations adjacent a wellbore, methods of
manufacturing the same, and uses of the cables in seismic and
wellbore operations. Designs for oilfield cables must strike a
balance between weight, strength, corrosion resistance and
materials and manufacturing resources. Wireline cables must support
their own weights plus the weights of downhole tool strings. This
invention addresses concerns by using an alloy-clad material with a
low density core. The outer clad is designed to be resistant to
corrosion, abrasion, and galling.
[0026] While this invention and its claims are not bound by any
particular mechanism of operation or theory, it has been discovered
that using certain alloys to form an alloy clad upon a low density
core in preparing an armor wire, provides lighter weight per length
electrical cables with resistance to corrosion, abrasion
resistance, and possess reasonably high strength properties. By low
density core it is meant the core is form substantially from a
material with a density up to about 4.8 g/cm.sup.3, for example,
from about 4.2 g/cm.sup.3 to about 4.8 g/cm.sup.3. In the case of
titanium and its alloys when used as a core, as it has a lower
density material than steel, the resulting wire weights are
significantly less. This lower weight increases strength-to-weight
ratio, enables the use of lighter duty well-service trucks, as well
as increases the reach into highly deviated wells.
[0027] Titanium or titanium alloys, when used alone as a cable
component, is known to be somewhat unsuitable for oilfield cable
application, particularly as titanium is subject to galling (damage
caused by adhesive friction) when titanium parts rub against each
other. As such, galling renders titanium difficult for an
application such as armor wires, where wires are in constant
contact with each other under high tensions. Galling resistance for
titanium in cables can be mitigated by expensive alloying also and
by creating an impurity layer on the surface of the wire. The
impurities that can be created on the wire surface cannot be
exposed to excessive torsional loading that the wire and the cable
is exposed to during manufacturing and deployment, and the
impurities can lead to potential fracture initiation sites.
However, inventors have discovered that placing a cladding over a
lightweight titanium or titanium alloy core can overcome the
problems described above, or at least in part. The clad material
also offers a significant increase in the corrosion resistance of
the wire. This is typically useful when the cable is used in highly
corrosive environments such as sour and highly deviated
wellbores.
[0028] In some embodiments of the invention, the lightweight armor
wires used in the cables are prepared from a metal billet made of a
low density titanium or its alloy core and a clad made of a
corrosion resistant metal, such as austenitic stainless steel,
Inconel.RTM., and the like. The clad may be extruded over the
titanium core or may be formed over the core and then seam-welded.
The billet is drawn to a smaller diameter to form armor wire stock.
The ratio of clad width to core width remains constant as the
billet is drawn to a smaller diameter. The completed armor wire
density or weight per length can be as much as about 40% less than
standard GIPS armor wire, with significant gains in strength to
weight ratios.
[0029] Cable embodiments of the invention generally include at
least one insulated conductor, and at least one layer of high
strength corrosion resistant armor wires surrounding the insulated
conductor(s). Insulated conductors useful in the embodiments of the
invention include metallic conductors, or even one or more optical
fibers. Such conductors or optical fibers may be encased in an
insulated jacket. Any suitable metallic conductors may be used.
Examples of metallic conductors include, but are not necessarily
limited to, copper, nickel coated copper, or aluminum. Preferred
metallic conductors are copper conductors. While any suitable
number of metallic conductors may be used in forming the insulated
conductor, preferably from 1 to about 60 metallic conductors are
used, more preferably 7, 19, or 37 metallic conductors. Components,
such as conductors, armor wires, filler, optical fibers, and the
like, used in cables according to the invention may be positioned
at zero helix angle or any suitable helix angle relative to the
center axis of the cable. Generally, a central insulated conductor
is positioned at zero helix angle, while those components a
surrounding the central insulated conductor are helically
positioned around the central insulated conductor at desired helix
angles. A pair of layered armor wire layers may be contra-helically
wound, or positioned at opposite helix angles.
[0030] Insulating materials useful to form the insulation for the
conductors and insulated jackets may be any suitable insulating
materials known in the art. Non-limiting examples of insulating
materials include polyolefins,
polytetrafluoroethylene-perfluoromethylvinylether polymer (MFA),
perfluoro-alkoxyalkane polymer (PFA), polytetrafluoroethylene
polymers (PTFE), ethylene-tetrafluoroethylene polymers (ETFE),
ethylene-propylene copolymers (EPC), poly(4-methyl-1-pentene)
(TPX.RTM. available from Mitsui Chemicals, Inc.), other
fluoropolymers, polyaryletherether ketone polymers (PEEK),
polyphenylene sulfide polymers (PPS), modified polyphenylene
sulfide polymers, polyether ketone polymers (PEK), maleic anhydride
modified polymers, perfluoroalkoxy polymers, fluorinated ethylene
propylene polymers,
polytetrafluoroethylene-perfluoromethylvinylether polymers,
polyamide polymers, polyurethane, thermoplastic polyurethane,
ethylene chloro-trifluoroethylene polymers (such as Halar.RTM.),
chlorinated ethylene propylene polymers, Parmax.RTM. SRP polymers
(self-reinforcing polymers manufactured by Mississippi Polymer
Technologies, Inc. based on a substituted poly (1,4-phenylene)
structure where each phenylene ring has a substituent R group
derived from a wide variety of organic groups), or the like, and
any mixtures thereof.
[0031] In some embodiments of the invention, the insulated
conductors are stacked dielectric insulated conductors, with
electric field suppressing characteristics, such as those described
in U.S. Pat. No. 6,600,108 (Mydur, et al.), incorporated herein by
reference. Such stacked dielectric insulated conductors generally
include a first insulating jacket layer disposed around the
metallic conductors wherein the first insulating jacket layer has a
first relative permittivity, and, a second insulating jacket layer
disposed around the first insulating jacket layer and having a
second relative permittivity that is less than the first relative
permittivity. The first relative permittivity is within a range of
about 2.5 to about 10.0, and the second relative permittivity is
within a range of about 1.8 to about 5.0.
[0032] Electrical cables according to the invention may be of any
practical design. The cables may be wellbore cables, including
monocables, coaxial cables, quadcables, heptacables, seismic
cables, slickline cables, multi-line cables, and the like. In
coaxial cable designs of the invention, a plurality of metallic
conductors surround the insulated conductor, and are positioned
about the same axis as the insulated conductor. Also, for any
cables of the invention, the insulated conductors may further be
encased in a tape. All materials, including the tape disposed
around the insulated conductors, may be selected so that they will
bond chemically and/or mechanically with each other. Armor wires
used in the invention make possible lightweight, lower modulus
wireline cables, especially desirable for downhole tractor
applications. Cables of the invention may have an outer diameter
from about 0.5 mm to about 400 mm, preferably, a diameter from
about 1 mm to about 100 mm, more preferably from about 2 mm to
about 15 mm.
[0033] Armor wires useful for cable embodiments of the invention,
may have titanium or its alloys placed at the core of the armor
wires. An alloy with resistance to corrosion and reduction of
galling is then clad over the core. The corrosion resistant alloy
layer may be clad over the low density core by extrusion or by
forming over the core. The corrosion and improved galling resistant
clad may be from about 50 microns to about 600 microns in
thickness. The material used for the corrosion and improved galling
resistant clad may be any suitable alloy that provides sufficient
corrosion resistance and abrasion resistance when used as a clad.
The alloys used to form the clad may also have tribological
properties adequate to improve the abrasion resistance and
lubricating of interacting surfaces in relative motion, or improved
corrosion resistant properties that minimize gradual wearing by
chemical action, or even both properties.
[0034] While any suitable alloy may be used as a corrosion
resistant alloy clad to form the armor wires according to the
invention, some examples include, but are not necessarily limited
to: beryllium-copper based alloys; nickel-chromium based alloys
(such as Inconel.RTM. available from Reade Advanced Materials,
Providence, R.I. USA 02915-0039); superaustenitic stainless steel
alloys (such as 20Mo6.RTM. of Carpenter Technology Corp.,
Wyomissing, Pa. 19610-1339 U.S.A., INCOLOY.RTM. alloy 27-7MO and
INCOLOY.RTM. alloy 25-6MO from Special Metals Corporation of New
Hartford, N.Y., U.S.A., or Sandvik 13RM19 from Sandvik Materials
Technology of Clarks Summit, Pa. 18411, U.S.A.); nickel-cobalt
based alloys (such as MP35N from Alloy Wire International, Warwick,
R.I., 02886 U.S.A.); copper-nickel-tin based alloys (such as
ToughMet.RTM. available from Brush Wellman, Fairfield, N.J., USA);
or, nickel-molybdenum-chromium based alloys (such as HASTELLOY.RTM.
C276 from Alloy Wire International). The corrosion resistant alloy
clad may also be an alloy comprising nickel in an amount from about
10% to about 60% by weight of total alloy weight, chromium in an
amount from about 15% to about 30% by weight of total alloy weight,
molybdenum in an amount from about 2% to about 20% by weight of
total alloy weight, cobalt in an amount up to about 50% by weight
of total alloy weight, as well as relatively minor amounts of other
elements such as carbon, nitrogen, titanium, vanadium, or even
iron. The preferred alloys are nickel-chromium based alloys, and
nickel-cobalt based alloys.
[0035] Cables according to the invention include at least one layer
of armor wires surrounding the insulated conductor. The armor wires
used in cables of the invention, comprising a low density core and
a corrosion resistant alloy clad may be used alone, or may be
combined with other types of armor wires, such as galvanized
improved plow steel wires, superaustenitic stainless steel armor
wires, or even wire rope armor wires, to form the armor wire
layers. Preferably, two layers of armor wires are used to form
preferred electrical cables of the invention.
[0036] Referring now to FIG. 1, a cross-sectional view of a typical
heptacable design. FIG. 1 depicts a cross-section of a t ypical
armored cable design used for downhole applications. The cable 100
includes a central conductor bundle 102 having multiple conductors
and an outer polymeric insulating material. The cable 100 further
includes a plurality of outer conductor bundles 104, each having
several metallic conductors 106 (only one indicated), and a
polymeric insulating material 108 surrounding the outer metallic
conductors 106. Preferably, the metallic conductor 106 may be a
copper conductor. The central conductor bundle 102 of a typical
prior art cables, although need not be, is typically the same
design as the outer conductor bundles 104. An optional tape and/or
tape jacket 110 made of a material that may be either electrically
conductive or electrically non-conductive and that is capable of
withstanding high temperatures encircles the outer conductor
bundles 104. The volume within the tape and/or tape jacket 110 not
taken by the central conductor bundle 102 and the outer conductors
104 is filled with a filler 112, which may be made of either an
electrically conductive or an electrically non-conductive material.
A first armor layer 114 and a second armor layer 116, generally
made of a high tensile strength galvanized improved plow steel
(GIPS) armor wires, surround and protect the tape and/or tape
jacket 110, the filler 112, the outer conductor bundles 104, and
the central conductor bundle 102.
[0037] FIG. 2 is a stylized cross-sectional representation of a
lightweight armor wire design. The armor wire 200 includes a low
density core 202, surrounded by a corrosion resistant alloy clad
204. An optional bonding layer 206 may be placed between the core
202 and alloy clad 204. The core 202 may be generally made of any
low density material such as, by non-limiting example, titanium and
its alloys. Examples of suitable alloys which may be used as core
strength members include, but are not necessarily limited to CP
Grades 1, 2, 3, etc., Beta-C, Ti-6A1-4V. The core strength member
202 can include Titanium core for low density, or even plated or
coated wires. When used, the bonding layer 206 may be any material
useful in promoting a strong bond between the high strength core
202 and corrosion resistant alloy clad 204. The microstructure
phase of the low density core can be alpha, alpha-beta or beta.
[0038] Referring now to FIG. 3, a cross-sectional representation of
a general cable design according to the invention which
incorporates two layers of armor wires. The cable 300 includes at
least one insulated conductor 302 and two layers of armor wires,
304 and 306. The insulated conductor 302 may be a heptacable,
quadcable, monocable, or even coaxial cable design. The armor wire
layers, 304 and 306, surrounding the insulated conductor(s) 302
include armor wires, such as armor wire 200 in FIG. 2, comprising a
low density core and a corrosion resistant alloy clad. Optionally,
in the interstitial spaces 308, formed between armor wires, as well
as formed between armor wires and insulated conductor(s) 302, a
polymeric material may be disposed.
[0039] Polymeric materials disposed in the interstitial spaces 308
may be any suitable material. Some useful polymeric materials
include, by nonlimiting example, polyolefins (such as EPC or
polypropylene), other polyolefins, polyaryletherether ketone
(PEEK), polyaryl ether ketone (PEK), polyphenylene sulfide (PPS),
modified polyphenylene sulfide, polymers of
ethylene-tetrafluoroethylene (ETFE), polymers of
poly(1,4-phenylene), polytetrafluoroethylene (PTFE),
perfluoroalkoxy (PFA) polymers, fluorinated ethylene propylene
(FEP) polymers, polytetrafluoroethylene-perfluoromethylvinylether
(MFA) polymers, Parmax.RTM., and any mixtures thereof. Preferred
polymeric materials are ethylene-tetrafluoroethylene polymers,
perfluoroalkoxy polymers, fluorinated ethylene propylene polymers,
and polytetrafluoroethylene-perfluoromethylvinylether polymers. The
polymeric materials may be disposed contiguously from the insulated
conductor to the outermost layer of armor wires, or may even extend
beyond the outer periphery thus forming a polymeric jacket that
completely encases the armor wires.
[0040] A protective polymeric coating may be applied to strands of
armor wire for additional protection, or even to promote bonding
between the armor wire and any polymeric material disposed in the
interstitial spaces. As used herein, the term bonding is meant to
include chemical bonding, mechanical bonding, or any combination
thereof. Examples of coating materials which may be used include,
but are not necessarily limited to, fluoropolymers, fluorinated
ethylene propylene (FEP) polymers, ethylene-tetrafluoroethylene
polymers (Tefzel.RTM.), perfluoro-alkoxyalkane polymer (PFA),
polytetrafluoroethylene polymer (PTFE),
polytetrafluoroethylene-perfluoromethylvinylether polymer (MFA),
polyaryletherether ketone polymer (PEEK), or polyether ketone
polymer (PEK) with fluoropolymer combination, polyphenylene sulfide
polymer (PPS), PPS and PTFE combination, latex or rubber coatings,
and the like. Each armor wire may also be plated with materials for
corrosion protection or even to promote bonding between the armor
wire and polymeric material. Nonlimiting examples of suitable
plating materials include copper alloys, and the like. Plated armor
wires may even cords such as tire cords. While any effective
thickness of plating or coating material may be used, a thickness
from about 10 microns to about 100 microns is preferred.
[0041] FIG. 4 is a cross-sectional representation of a heptacable
design according to the invention, including two layers of armor
wires. The cable 400 includes two layers of armor wires, 402 and
404, surrounding a tape and/or tape jacket 406. The armor wire
layers, 402 and 404, include armor wires, such as armor wire 200 in
FIG. 2, comprising a low density core and a corrosion resistant
alloy clad. The interstitial space within the tape and/or tape
jacket 406 comprises a central insulated conductor 408 and six
outer insulated conductors 410 (only one indicated). The
interstitial space within the tape and/or tape jacket 406, not
occupied by the central insulated conductor 408 and six outer
insulated conductors 410 may be filled with a suitable filler
material, which may be made of either an electrically conductive or
an electrically non-conductive material. The central insulated
conductor 408 and six outer insulated conductors 410, each have a
plurality of conductors 412 (only one indicated), and insulating
material 414 surrounding the conductors 412. Preferably, the
conductor 412 is a copper conductor. Optionally, a polymeric
material may be disposed in the interstitial spaces 416, formed
between armor wires, as well as formed between armor wires and tape
jacket 406.
[0042] FIG. 5 represents, by stylized cross-section, a monocable
design according to the invention. The cable 500 includes two
layers of armor wires, 502 and 504, surrounding a tape and/or tape
jacket 506. The armor wire layers, 502 and 504, include armor
wires, such as armor wire 200 in FIG. 2, comprising a high strength
core and a corrosion resistant alloy clad. The central conductor
508 and six outer conductors 510 (only one indicated) are
surrounded by tape jacket 506 and layers of armor wires 502 and
504. Preferably, the conductors 508 and 510 are copper conductors.
The interstitial space formed between the tape jacket 506 and six
outer conductors 510, as well as interstitial spaces formed between
the six outer conductors 510 and central conductor 508 the may be
filled with an insulating material 512 to form an insulated
conductor. Optionally, a polymeric material may be disposed in the
interstitial spaces 516, formed between armor wires, as well as
formed between armor wires and tape jacket 506.
[0043] FIG. 6 illustrates a method of preparing some armor wires
useful in cables according to the invention. Accordingly, a low
density core A is provided. At point 602, the core A may optionally
be coated with a bonding layer B, such as brass using a hot dip or
electrolytic deposition process. At point 604 the optional bonding
layer coated core A is brought into contact with a sheet of
corrosion resistant alloy material C, such as, by nonlimiting
example, Inconel.RTM. nickel-chromium based alloy. The alloy
material C is used to prepare the corrosion resistant alloy clad.
At points 606, 608, and 610, the alloy material is formed around
the optional bonding layer core A, using, for example, rollers.
Such forming of the alloy material is done at temperatures between
ambient temperature and about 850.degree. C. Additionally, the
optional bonding layer B may flow and to sufficiently provide a
slipping interface between the high strength core A and the
corrosion resistant alloy clad comprised of alloy material C. At
point 612, the wire is drawn down (not necessarily to scale as
illustrated) to a final diameter to form the armor wire D. The
drawn thicknesses of the optional bonding layer coated core A alloy
clad C may be proportional to the pre-drawn thickness.
[0044] FIG. 7 illustrates another method of preparing armor wires.
According to this next method, a low density core A is provided,
and at point 702, the high strength core A is optionally coated
with a bonding layer B. At point 704 the optional bonding layer
coated core A is brought into contact with two separate sheets of
corrosion resistant alloy material, D and E, to form the corrosion
resistant alloy clad. At points 706 and 708, the sheets of alloy
material are formed around the optional bonding layer coated core
A. At point 710, the wire is drawn down to final diameter to form
the armor wire F.
[0045] FIG. 8 illustrates yet another method of preparing armor
wires, an extrusion and drawing method. Accordingly, a high
strength core A is provided, and at point 802, and corrosion
resistant alloy clad B is extruded over core A. The material
forming the corrosion resistant alloy clad B may be hot or cold
extruded onto the core A. At 804, the wire is drawn down (not
necessarily to scale as illustrated) to a final diameter to form
the armor wire C. Further, the high strength core A may be
optionally coated with a bonding layer prior to extruding the
corrosion resistant alloy clad B.
[0046] Referring now to FIG. 9, a cross-sectional generic
representation of some cables of the invention which include a
polymeric material disposed about the armor wires. The cables
include an insulated conductor core 902 which comprises insulated
conductors in such configurations as heptacables, monocables,
coaxial cables, slickline cables, or even quadcables. A polymeric
material 908 is contiguously disposed in the interstitial spaces
formed between layers of armor wires 904 and 906, and interstitial
spaces formed between the armor wires 904 and core 902. The layers
of armor wires 904 and 906 are composed of armor wires comprising a
low density core and a corrosion resistant alloy clad. The
polymeric material 908 may further include short fibers. The inner
armor wires 904 are evenly spaced when cabled around the core 902.
The polymeric material 908 may extend beyond the periphery of outer
armor wire layer 906 to form a polymeric jacket thus forming a
polymeric encased cable 900.
[0047] The materials forming the insulating layers and the
polymeric materials used in the cables according to the invention
may further include a fluoropolymer additive, or fluoropolymer
additives, in the material admixture used to form the cable. Such
additive(s) may be useful to produce long cable lengths of high
quality at high manufacturing speeds. Suitable fluoropolymer
additives include, but are not necessarily limited to,
polytetrafluoroethylene, perfluoroalkoxy polymer, ethylene
tetrafluoroethylene copolymer, fluorinated ethylene propylene,
perfluorinated poly(ethylene-propylene), and any mixture thereof.
The fluoropolymers may also be copolymers of tetrafluoroethylene
and ethylene and optionally a third comonomer, copolymers of
tetrafluoroethylene and vinylidene fluoride and optionally a third
comonomer, copolymers of chlorotrifluoroethylene and ethylene and
optionally a third comonomer, copolymers of hexafluoropropylene and
ethylene and optionally third comonomer, and copolymers of
hexafluoropropylene and vinylidene fluoride and optionally a third
comonomer. The fluoropolymer additive should have a melting peak
temperature below the extrusion processing temperature, and
preferably in the range from about 200.degree. C. to about
350.degree. C. To prepare the admixture, the fluoropolymer additive
is mixed with the insulating jacket or polymeric material. The
fluoropolymer additive may be incorporated into the admixture in
the amount of about 5% or less by weight based upon total weight of
admixture, preferably about 1% by weight based or less based upon
total weight of admixture, more preferably about 0.75% or less
based upon total weight of admixture.
[0048] Cables of the invention may include armor wires employed as
electrical current return or supply wires which provide paths to
ground for downhole equipment or tools. The invention enables the
use of armor wires for current return while minimizing electric
shock hazard. In some embodiments, a polymeric material isolates at
least one armor wire in the first layer of armor wires thus
enabling their use as electric current return wires.
[0049] The present invention is not limited, however, to cables
having only metallic conductors. Optical fibers may be used in
order to transmit optical data signals to and from the device or
devices attached thereto, which may result in higher transmission
speeds, lower data loss, and higher bandwidth.
[0050] The particular embodiments disclosed above are illustrative
only, as the invention may be modified and practiced in different
but equivalent manners apparent to those skilled in the art having
the benefit of the teachings herein. Furthermore, no limitations
are intended to the details of construction or design herein shown,
other than as described in the claims below. It is therefore
evident that the particular embodiments disclosed above may be
altered or modified and all such variations are considered within
the scope and spirit of the invention. In particular, every range
of values (of the form, "from about a to about b," or,
equivalently, "from approximately a to b," or, equivalently, "from
approximately a-b") disclosed herein is to be understood as
referring to the power set (the set of all subsets) of the
respective range of values. Accordingly, the protection sought
herein is as set forth in the claims below.
* * * * *